1. Field of the Invention
This invention relates to a process for the production of trifluoromethyl benzaldehydes, useful as chemical intermediates in the further production of pesticides.
2. Prior Art
Benzaldehydes are useful for a variety of industrial applications and various processes for the production of benzaldehydes are found in the literature.
U.S. Pat. No. 4,111,998 discloses a process for the preparation of an aromatic aldehyde by reduction of the corresponding acid chloride using hydrogen in the presence of a palladium catalyst and a tertiary amide.
U.S. Pat. No. 4,383,949 discloses a process for the preparation of a 3-bromo-4-fluorobenzaldehyde acetal by reaction of the corresponding benzoic acid halide with ammonia to form an imide, dehydrating the imide to form 3-bromo-4-fluorobenzonitrile, and reacting the nitrile with formic acid in the presence of a catalyst to form the benzaldehyde. The benzaldehyde is then converted to the benzaldehyde acetal.
U.S. Pat. No. 2,945,862 teaches a process for the preparation of aldehydes by catalytic hydrogenation of the corresponding nitriles in the presence of an aqueous phase and in the presence of a metal catalyst such as reduced nickel.
U.S. Pat. No. 4,500,721 discloses a process for the preparation of benzaldehydes from benzonitriles by catalytic reduction in the presence of an acid using a Raney nickel catalyst pretreated with a copper salt.
T. vanEs and B. Staskun, Organic Syntheses, 51, 20 (1971) describe the reduction of an aromatic nitrile to an aldehyde in the absence of hydrogen using a stoichiometric excess of nickel/aluminum alloy reagent as a reducing agent in 75% formic acid. The process is not a catalytic reduction but rather reduction where the nickel/aluminum alloy is a sacrificial reagent.